US2591122A - Crossbelt magnetic separator - Google Patents

Description

April 1, 1952 K. A. BLIND CROSSBELT MAGNETIC SEPARATOR Filed Dec. 5. 1947 3 Sheets-Sheet 1 197701NEV151 Ap l, 1952 K. A. BLIND CROSSBELT MAGNETIC SEPARATOR 5 Sheets-Sheet 2 Filed Dec. 5, 1947 INVENTOR. a

April 1, 1952 K. A. BLIND CROSSBELT MAGNETIC SEPARATOR 3 Sheets-Sheet 3 Filed Dec. 5, 1947 10 I INVENTOR. BY Q.

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Patented Apr. 1, 1952 CRO-SSBELT MAGNETIC SEPARATOR Karl A. Blind, Thiensville, Wis., assignor to Dings Magnetic Separator 00., Milwaukee, Wis., a corporation of Wisconsin Application December 3, 1947, Serial No. 789,497

3 Claims. 1

My present invention relates in general to improvements in the magnetic separation art, and relates more specifically to various improvements in the construction and operation of equipment for effecting separation of magnetic particles from a mixture of magnetic and non-magnetic granular materials while such mixture is advancing through one or more fields of magnetic influence.

The principal object of the present invention is to provide improvements in magnetic separators of the general type forming the subject of my copending application Serial No. 747,229, filed May 10, 1947, whereby the efficiency and capacity of such separators may be augmented.

In my prior application above identified, I have shown'and described an improved cross-belt type of magnetic separator having a main conveyor for transporting mixed magnetic and non-magnetic granular material along a definite path, a transversely movable auxiliary conveyor disposed somewhat above and spanning the said path, a pair of lower and upper complementary zone poles disposed beneath and above the main and auxiliary conveyors respectively, and means for energizing the zone poles so as to create a field of magnetic influence at the gap between the conveyorssufiiciently intense to separate magnetic particlesfrom the bulk mixture and to suspend these particles from the advancing auxiliary conveyor. This prior cross-belt separator embodies a lower zone pole having a smooth fiat face coactting with the underside of a main mixed material conveying belt, and a complementary zone pole coacting with top surface of an auxiliary magnetic particle removing cross-belt, the latter zone pole having a, series of parallel wedge faces or ridges theedges of which are spaced equidistant from the flat face of the lower pole and extend in the direction of travel of the auxiliary belt. In accordance with my prior disclosure, two sets of these specially constructed complementary zone poles were energized by means of a common pair of coils and were associated with successive advancing portions of the main conveyor belt, thus providing two spaced separating zones or magnetic fields of equal intensity each having a pair of coacting relatively fixed zone poles composed of material having uniform permeability throughout.

I have now discovered that the efficiency of such serrated or ridged zone poles may be materially enhanced by providing ridge tips or edges composed of material having higher permeability than that utilized in the remaining major portions of the poles, thereby causing more of the flux tubes to pass through the air gap remote from the ridge apiece and providing more uniform distribution of these tubes throughout the magnetic zone thus also augmenting the lifting force. I have also found that in order to increase the utility and effectiveness of such cross-belt sepators and to adapt them for the treatment of materials having variable magnetic characteristics. it is desirable to vary the width of the air gap between the complementary zone poles; and I have moreover discovered that more efilcient removal of the magnetic particles may also be accomplished by providing a succession of magnetic separating units disposed along the path of advancement of the mixed material and each having a set of coacting zone poles provided with independent magnetizing coils, the auxiliary belts of the successive units being movable in opposite directions while the belts of alternate units move in the same direction transversely of the main conveyor path. These several features applied to a cross-belt magnetic separator, have been found to materially increase the efficiency, to enhance its flexibility and adaptability, and to augment its capacity.

It is therefore a more specific object of the present invention to provide an improved zone pole construction for magnetic separators, and which is especially adapted for advantageous embodiment in the cross-belt type of separator.

Another specific object of the invention is to provide an improved zone pole assemblage for magnetic separators wherein the air gap between complementary sets of poles may be readily anlarged or diminished. V

A further specific object of my invention is to provide an improved unit for cross-belt magnetic separators or the like, wherein a set of complementary zone poles is energized and caused to cooperate with main and auxiliary material conveyors so as to most effectively separate magnetic from non-magnetic particles being constantly advanced by the conveyors.

Still another specific object of the invention is to provide an improved cross-belt magnetic separator assemblage embodying a main conveyor belt having a succession of independent local interchangeably similar separating units disposed at spaced intervals therealong and adapted to deliver removed magnetic particles in opposite directions away from the path of advancement of the bulk material by the .main conveyor.

An additional specific object of the present invention is to provide various improvements in the construction and operation of cross-belt magnetic separators whereby highly efficient automatic functioning results and which may be conveniently adjusted to meet varying conditions of use.

These and other specific objects and advantages of the invention will be apparent from the following detailed description.

A clear conception of the improved features. and of the mode of constructing and operating a typical multi-unit cross-belt magnetic. separator embodying the invention, may be had by referring to the drawings accompanying and forming a part of this specification wherein like reference characters designate the same or similar parts in the various views.

Fig. 1 is a side elevation of a typical multi-unit cross-belt magnetic separator assemblage embodying features of the. present invention;

Fig; 2' is a top view ofthe multi-unit magnetic separator of Fig. 1', showing the same in action;

Fig. 3 is a somewhat-enlarged end view of the multi-unit cross-belt magnetic. separator, looking toward the main endless conveyor drive;

Fig.4, is a similarly enlarged transverse crosssection through the same magnetic separator, takenalong, the line 4-4 of Fig. 1' and'looking in the 'direction of thearrows; V

'Fig. 5 is a. likewiseenlarged transverse crosssection. through the same magnetic separator, taken alon the line 5-5 of Fig. 1 and looking inthedirectionof'the arrows;

Fig. 6. is a further enlarged, transverse crosssection through the assemblage, similar to that offFigr 5, but showing additional improved details of construction;

' Fig. 7 is alikewise further enlarged side view of one of theimproved magnetic separator units;

Eig.j8 is a still further enlarged fragmentary cross-section through a set of complementary asymmetrical, zone poles, theisection having been taken. along theline. 8-8 of Fig. 6;

Fig, '9} is. a similar cross-section througha succeeding adjacent set of the same type of zone poles; and

Fig. 1-0 isan elevation of a complementary set of symmetrical zone poles embodying the innl i While the invention has been, shown and describedherein as being especially advantageously applicable to a multiunit cross-belt magnetic separator having a series of interchangeably similarreversely disposed magnet units cooperating with a common main conveyor belt, it is not my desire or intention to unnecessarily limit the scope'or utility of the improved features by virture. of this restricted embodiment, since some of these features are obviously more generally applicable to other types of magnet assemblages.

Referring to the. drawings, the typical multi- V unitcross-belt magnetic separator, shown therein, comprises in general an elongated rigid frame composed of'a. pair of laterally spaced parallel 7 channel bars ll interconnected by tie-bolts I2;

bars H, and having an upper stretch or, run for constantly advancing a relatively thin layer I1 of granular material from oneendof the frame toward. the other; amaterialsupply'hopper I8 .mounted upon theframe near the feed end of V the conveyor I 4; avariable speed propelling mo-i 'tor T9 for the conveyor [4 mounted upon the opposite end of the frame and being drivingly' connected to the pulley l6 through reduction gearing 26; a low intensity magnetic scalping unit 25 mounted upon the main frame and cooperating with the bulk material layer I! near the feed hopper l8; and a succession of interchangeably similar but reversely disposed higher intensity cross-belt magnetic separating units 23,

24 cooperating with the advancing layer H at spaced intervals between the scalper 2| and the the hopper It, the. reduction gearing 20, the

scalping unit 2i, and the separating units 23, 24; The lower stretch or run of the'main conveyor belt may be supported against excessive sagging by a succession of rollers 25 journal-led in bearings mounted uponthe channel bars H. as shown in Fig. 5; and while the belt carrying pulley: it ismounted in fixed bearings; the opposite end pulley I5 is journalledinmovable bearings which may be adjusted with the aid of tensioningdevices 26' so as to properlystretch the beltruns; see Figs. 1 and 2. Themater'ial supply hopper 18 located at the feed end of the upper run of the main conveyor l4, should be abundantly filled with bull; material consisting of; a mixture, of magnetic and non-magnetic particles, and this hopper i8 should also be adapted-to deposit arelativelythin and uniform layer H of the mixed materials upon the constantly advancing upper run of the main conveyor l4. 7

The main conveyor propelling motor I9 isprefierably of; the variable speed typeso that th'e convey'or M1 and the layer it of' material restin thereon may be continuously advanced atany selected speed; and the initial or scalping unit 2] is, preferablyof relatively low intensity electromagnetic type adapted to promptly separate and remove a considerable portion of the highly'mag netic particles embodied in the advancing layer i l; This initial. unit 211 is shown generally in Figs..1.and 2, .and more .in detail in Fig. 4,.and consists primarily o'fa top pol'eassembly 28, and a flower beltsupport '27 separatedgby. an air gap through which the layer IT of mixedlmater'ia'ls is advanced by the main conveyor Mooacting'with thesupport 21; anendless auxiliary crossrheltlil coacting with. pulleys 3,1 3! and having. a. lower stretch movabletransyerselyacross themain conveyorl I14 in: a close proximity-to the upper pole (28,; a. variable. speed electric motor-33. drivingly associatediwith the pulley 39 at one-endof the conveyor belt 29; a magnetic particle discharge chute. 34 disposed beneath thelower run. of the beltza and below the pulley 3l beyond the main conveyor 14.; and electric coilsv 35 for energize in the magnets so. as. to. produce an 'fiel'd of magneticinfluence at thelair-gap, these coils 35 being located between the lower and upper stretches of the conveyor 'beltzt. The scalping unit, Ell-is. of relatively well known, construction and operation, and is preferably-located nearthe tion anddisposition, and. each of these individual units comprises alower; pole support v36 Lmou'nted upon the mainframe channel bars l'l an'dcarrying Opposite upright side plates 37, 38 which coact with a top plate 36 to provide a magnetic loop; a lower zone pole 45 having a smooth top face coacting with the bottom surface of the upper run of the main conveyor I4, and also having an inclined lower face resting upon the upper surface of an adjusting wedge 4! which in turn rests upon the loop support 36; an upper zone pole 43 spaced vertically from the complementary zone pole to provide an air gap and being detachably secured to and suspended from a magnetizing core 44 which is carried by the top plate 39 of the loop and is embraced by energizing windings or coils 45; an endless auxiliary cross-belt 46 coacting with upper and lower pulleys 41, 48 journalled for rotation in bearings carried by the loop frame, the belt 4% having a lower stretch movable across the main conveyor I4 in contact with the lower face of the upper, zone pole 43; a variable speed electric motor 49 drivingly associated with one of the upper auxiliary belt supporting pulleys 4i; and a magnetic particle discharge chute 5i] suspended from the loop beneath the lower stretch of the belt 46 and below the motor 49 laterally beyond the main conveyor belt I4.

While all of these cross-be1t units 23, 24 are of identical construction, the successive units are reversed relative to the main belt M which passes through the air gaps of all units, so that the lower runs of the successive cross-belts 46 travel in opposite directions and deliver separated magnetic particles 5| to successive discharge chutes 50 located on opposite sides of the main conveyor l4. Each of the cross-belt propelling motors 49 may be operated at any selected speed, and the vertical width of the air gap in each unit 23, 24 may be varied to suit the operating conditions at the successive separating zones, either by raising or lowering the lower zone pole 40 with the aid of the adjacent supporting wedge 4|, or by replacing the removable upper zone pole 43 with another having greater or lesser height. The lower zone pole 46 of each complementary set is fixed against lateral displacement by means of several guide screws 53 with which compression springs 54 coact to constantly urge the pole 40 against the adjoining wedge 4|, and each of these wedges 4| is adapted to be shifted laterally beneath the adjacent pole 48 to vary the air gap, with the aid of a threaded rod 55 coacting with screw threads in the wedge and journalled for rotation in the adjacent loop support 36, the rod 55 being rotatable by means of a hand wheel 56, see Fig. 6. The wedge 4| of each unit is also provided with slots 51 as shown in Figs. 6 and 9 for permitting adjustment without interference by the screws 53, and a suitable gage 58 for indicating the degree of adjustment may also be provided.

The upper zone pole 43 of each complementary pair is provided with a gap widening pole 59 projecting from its material delivery end, and is detachably secured to the lower end of the adjacent core 44, by means of scr ws as coacting with flange plates 6| secured to the pole 43. The widening poles 59 may be detachably attached to their supporting poles 43 by bolts 63 piercing the latter, and by replacing the upper zone poles 43 with others having different height, the vertical height of the adjacent air gaps may be readily varied. The face of each upper pole 43 which coacts with the adjacent cross-belt 46, is preferably of improved construction, and as shown in 'Figs. 8 and 9, the bottom face of each pole 43 is provided with a series of parallel asymnletrical wedge shaped ridges 64 extending thereacross and each having a lower triangular edge portion 65 formed of magnet material having considerably higher magnetic permeability than the upper portion of the pole. These edge portions 65 may be secured to the upper portions of the poles in any suitable manner as by fusion of metals, and.

the gaps between the ridges are preferably spanned by angular sectional strips 66 of nonmagnetic material welded or otherwise secured to the zone pole 43, so as to provide a smooth and approximately plane bearing surface for the belt 46, see Figs. 8 and 9.

In the asymmetrical wedge ribbed type of zone pole 43 shown in Figs. 8 and 9, the main conveyor belt l4 should always advance through the zone of magnetic influence in a direction approaching the inclined sides of the ridges 64 and away from the perpendicular bounding surfaces thereof, in order to obtain best and most efilcient distribution of the flux tubes, but the lower face of the upper zone pole 43 may also be advantageously formed with symmetrical ridges 64' each having a lower triangular edge portion 65 of material having high magnetic permeability, as illustrated in Fig. 10. These modified ridges 64 provided with special lower tip portions 65', also span the zone pole 43 and will quite effectively distribute the flux tubes throughout the magnetic field or zone with the conveyor belt travelling therethrough in either direction, but they are not quite as effective theoretically as the asymmetrical ridges 64. As in the embodiment of Figs. 8 and 9, the gaps between the modified ridges 64' of Fig. 10, may also be spanned by non-magnetic strips 66 in order to provide a smooth bearing surface for the belt 46.

It has been found by actual test, that saturation or high concentration of magnetic fiux occurs at and near the apices of the ridges of the pole pieces 43, and it is well known that if a magnetic circuit is saturated beyond approximately 22,000 gausses, additional magnetomotive force or ampere turns will increase the'amount of field in the same proportion as the added magnetomotive force impressed upon the circuit. In other words, the advantage of ferric permeability is lost and the material near the tips of the pole ridges could be virtually replaced by air or a vacuum. Effective lifting force can be obtained:

only with maximum taper of the flux tubes extending from the upper pole tips or ridges to the. lower pole. Any additional amount of flux will therefore pass through the air gap away from each apex, thus enlarging the pick-up zone but reducing the field intensity, so that the gradient of the field is materially reduced. The geometrical distribution of the field will then be equivalent to that of a field existing in the gap if the ridge tips were rounded off with a large radius,

but this objection can be eliminated by forming.

and the result is increased attraction or liftingforce.

When the improved cross-belt magnetic separator has been properly constructed and assembled as herein described, it may be placed in normal operation by merely supplying the hopper l8 with an abundance of mixed material, by energizing the magnetcoils .35, 4 5, and by operating, the electric motors i9, 33, 49 to cause the endless conveyor belts M, 2,9, 49. to advance in the .di-

rections indicated by the several arrows associated with these belts in the various views. The continuously advancing relatively thin layer ll of the mixture resting upon the upper stretch of the :main conveyor M. will be carriedprogressively past .the scalper unit 2| and past the. series of reversely disposedcross- belt units 23, 24, and the magnetic particles .5! of the'mixture will be automatically separated and removed while the residual non-magnetic particles will ultimately be discharged from the end of the main conveyor I4 beneath its propelling motor [9. The scalping unit 2! removes a considerable portion of the highly magnetic particles 5! and the cross-belt 29 thereof removes these separated particles .from the initial separating zone and delivers them by gravity into the discharge chute 34. The sub-- sequent units '23, 24., gradually likewise separate and remove more and more of the magnetic particles 5|, and the .belts 46 of these units likewise deliver the particles 5! to the successive discharge chutesfiiilocated on opposite. sides of the main conveyor belt i 3, so. that very little valuable material remains in the. residue discharged at the delivery end of themain conveyor.

The speed of the main conveyor belt i i may be varied to insure maximum capacity, and the speeds of the auxiliary cross-belts 2s, es. of successive independent units 21,. it may also be varied independently of each other soas to in. sure maximum efficiency. Thentoo, the vertical widths of the gaps at the several separating zones 'may be quickly andconveniently varied or adjusted to meet different operating conditions, either by substituting upper zone poles 43 of different. heights, or by merely moving the wedges M with the aid. of the hand wheels 5%, and the latter adjustment may be effected at anyof the separating fields independently of all others.

It is to be noted that when a wedge M is moved improvements inthe. construction of :magnetic separators whereby the. capacity and efiiciency thereof may be materially enhanced, which may be accurately adjusted and manipulated to most effectively treat materials having diiierence characteristics. The improved upper zone pole structure having ridge tips of high permeability,

makes it possible to. obtain. maximum lifting efiectthroughout the entire separating zones, and the removability of these upper poles combined with the vertical adjustability of the lower zone poles 49. also makes it possible to readily vary the magnitude of the so as. to insure most efficient separation of the magnetic particles 5i from mixed materials having a wide range of characteristics. The provision of interchangeably similar cross-belt units 23, 24'not only reduces the cost of construction of the entire separator assemblage to a minimum, but also enables the capacity of the separator to be enlarged or diminished by merely providing more or, less of these units cooperating with a common main conveyor [4; and by making these units 23, 24. independently controllable. it: is posand extending across the major portion of the interior of said loop but being spaced. from said bottom member, an energizing coil surrounding siblerto obtain most effective separation at each a of: the. successive zones. The reversal. of the sucsaid core within said loop, a main mixedimatecessive units 2.3., '24 moreover tends to agitate the particles of the advancing layer I! so as to free the magnetic particles from the non-magnetic material, and by providing for variation in speed of travel of' the belts I i, 29, 46 both the bulk material and the separated particles may be advanced at maximum speed commensurate with greatest capacity.

While the provision of ridge tips 55 having high magnetic permeability is an important feature of my invention, the relative adjustabi-lity oi the zone poles it, 43 so as to vary the intervening gap is also important. The wedge adjustment permits the lower pole Hi to be raised or lower without shifting it laterally, since the screws 53 positively prevent such lateral shifting and the springs E i always maintain effective contact between the wedge. 31 and the adjacent. surfaces of the pole to and support 36. The non-magnetic strips 63 provide smooth bearing surfaces for the cross-belts 15 without interfering with the effectiveness of the ridged or serrated pole faces, and the ridges at, st may be formed either asymmetrical as in Figs. 8 and 9, or symmetrical as in Fig. 10 and anydes'ired number of these ridges may be provided. The invention has proven highly successful and satisfactory in actual use, and while all features have benshown as being applicable to cross-belt separators some of these features are obviously more generally applicable to other types of magnetic separators;

It should be understood that it is not desired to limit this invention to the exact details of construction or to the precisemode. of

the interior of said loop but being spaced from said bottom member, anenergizing coil surroundingsaid core within said loop, a main mixed. material conveyor movable through the space between said core and said bottom membenan auxiliary magnetic material conveyor also movable through said space across and above said main conveyor and being separated from the latter. by a magnetic *field gap, an upper magnet ll ole interposed between said core and said auxiliary conveyor, a lower magnet pole interposed between said main conveyor and said'bottom. member and having a plane lower surface spaced from andinclined toward and along the upper plane surface of said bottom member, and a'wedge of magnetic materialcoacting with said plane. reiativelyrinclined surfaces and being adjustable longitudinally of said bottom member to vary the size of the gap between said conveyors.

2. In a magnetic separator, a continuous magnetic loop having opposite side members-firmly interconnected by rigid top and bottom members.

a magnetic. core suspended from said top member V rial conveyor movable through the space between said core and said bottom member, an auxiliary magnetic material conveyor also movable through said space across and above said main conveyor and being separated from the latter by a magnetic field gap, an upper magnet .pole interposed between said core and said auxiliary conveyor, a lower magnet pole interposed between said main conveyor and said bottom member and having a plane lower surface spaced from and inclined toward and along the upper plane surface of said bottom member, a wedge of magnetic material coacting with said plane lower pole and bottom member surfaces and extending entirely across the lower pole and longitudinally of the bottom member, and a jack screw coacting with a side of said loop and with said wedge for ad justing the latter along said bottom member to vary the size of said field gap.

3. In a magnetic separator, a continuous mag netic loop having opposite side members firmly interconnected by rigid top and bottom members, a magnetic core suspended from said top member and extending across the major portion of the interior of said loop but being spaced from said bottom member, an energizing coil surrounding said core within said loop, a main mixed material conveyor movable through the space between said core and said bottom member, an auxiliary magnet material conveyor also movable through said space across and above said main conveyor and being separated from the latter by a magnetic field gap, an upper magnet pole interposed between said core and said auxiliary conveyor, a

10 lower magnet pole interposed between said main conveyor and said bottom member and having a plane lower surface spaced from and inclined toward and along the upper plane surface of said bottom member, a wedge of magnetic material coaeting with said plane lower pole and. bottom member surfaces and extending entirely across the lower pole and longitudinally of the bottom member, a jack screw coacting with a side of said loop and with said wedge for adjusting the latter along said bottom member to vary the size of said field gap, and resilient means for constantly urging said lower pole and said bottom member into intimate contact with said wedge.

KARL A. BLIND.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 825,672 Mofiatt July 10, 1906 1,303,397 Rowand May 13, 1919 1,310,802 Manegold July 22, 1919 1,366,979 Ulbrich Feb. 1, 1921 1,490,792 Woodworth Apr. 15, 1924 1,522,343 Thom Jan. 6, 1925 1,956,760 Forrer May 1, 1934 2,511,484 Stearns June 13, 1950 FOREIGN PATENTS Number Country Date 309,950 Great Britain Dec. 12, 1929

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